1. Field of the Invention
This invention relates to a process for the manufacture of a sleeve-shaped printing form for a printing machine form cylinder, and more particularly, to a process for fabricating, from a plate-shaped blank, a printing form sleeve having a continuous circumferential surface. Printing forms fabricated in accordance with the present invention are especially useful for offset printing applications.
2. Description of the Prior Art
A printing form sleeve for offset printing produced by a conventional process is disclosed in German Patent Application P41 40 768. This sleeve can be used in combination with a form cylinder having no grooves or clamping segments which is already known, e.g., from German Patent DE-PS 27 00 118. For this purpose, a plate is cut to dimensions corresponding to the circumference and width of the form cylinder and is provided, using a plate punch, with a register device in the form of a peg-hole system. The blank which conforms to the required dimensions must be cut to length in an accurate manner. This is done with special plate shears. The blank is bent or otherwise manipulated to form a tubular shape, and is clamped in a welding device with the contiguous edges in exact alignment or registration. The contiguous edges of the plate thus forming the beginning and end of the printing form can then be welded together longitudinally, preferably by means of a neodymium-YAG laser.
The prior German Patent Application P 43 11 078 further discloses a device in which the plate which has been cut to size need only be inserted, whereupon the plate can be bent into a sleeve shape and the plate edges forming the beginning and end of the printing form can be positioned in exact register for the purpose of laser welding. Disadvantageously, the plate shears used to cut the plate-shaped blank to the desired length, which cutting must be carried out very accurately, are very expensive.
Accordingly, it is an object of the present invention to provide an improved printing form fabrication process in which the need for plate shears is obviated and in which accurate cutting of the plate-shaped blank to the required dimensions is ensured.
It is a further object of the present invention to provide a printing form which can be manufactured in a simple and economical manner.